The minimal number of trials depends on how successfull you are.How quickly you are sucessfull shows how confident in yourself you are.

The time & number of sucessfull trials are tied, you should never separate them when judging an ABX log.

With F2K ABX component, 8 sucessfull trials in a row (& if all successfull in a row, it usually means quick) trials is the minimum for me.

As soon as you begin to fail you can easyly increase to 10 or 12 to try to "erease" your failures.In this case if you fail once or twice you can usually still get a signifiant result although it usually means the ABXing was hard, & by consequence longer as you begin to hesitate.

Usually if you begin to fail more than 3 times on 12 trials, it begins to be so hard & you have so much hesitation that it begins to take forever to ABX. At this stage I usually give up by myself & declare that I cannot ABX as in general it means I am not sure that the audio part I am focusing on actually contains any real artefact.

I never said I judged this test valid, I only gave my opinion about what is a valid methodology for me. I usually only trust ABXer which I have personnaly double tested, so I don't know if it's valid for me & honnestly I don't care as I ain't gonna re-test this.